Originally Posted by Baever
He's a bit dead at the moment...
http://www.wowhead.com/?item=32483
The Skull of Gul'dan was a powerful demonic artifact created from the skull of the orc sorcerer Gul'dan. Used for a plethora of demonic activity, from opening portals to corrupting the forests of Ashenvale, its powers were finally consumed by Illidan Stormrage. Although weakened, the skull still holds power and is in Illidan's possession.